Communication performed beyond a line of sight of a radio wave, of communication performed using a radio wave, is called over-the-horizon communication or over horizon transmission (OH) communication. The over-the-horizon communication is used in communication between distant points where the distance between transmission and reception points exceeds 100 km or between points having an obstacle therebetween such as in a mountain range. Further, the over-the-horizon communication is used for build-out of a temporary communication line at the time of disaster or in the event of an emergency.
By the way, many of wireless communication systems perform transmission/reception of a radio wave, using a predetermined polarized wave such as a horizontal polarized wave, a vertical polarized wave, or a circularly polarized wave, from viewpoints of a decrease in coherence and effective use of frequency resources. In such communication systems, work to adjust polarization planes of radio waves transmitted/received between communication devices that perform communication is necessary.
Regarding polarization plane adjustment technologies in wireless communication systems, Patent Literature 1 describes a polarization plane adjustment technology in a reception device that receives a radio wave sent by a communication satellite. The reception device described in Patent Literature 1 includes a level detection circuit that detects a level of an electrical signal converted from the radio waves from the communication satellite, the radio waves having been received by a primary radiator, and a motor built in the primary radiator and which rotates the polarization plane. The wireless device controls the motor to make the level of the electrical signal supplied from the primary radiator and detected by the level detection circuit large, to adjust the polarization plane of the primary radiator to correspond to the polarized wave of the radio wave from the communication satellite.